Various aspects of the present invention relate generally to virtual machines, and more particularly, to managing virtual machines.
In recent years, virtualization technology has been widely used in many situations in order to improve the efficiency of information technology (IT) resources and applications. Virtualization technology can instantly assign resources, applications, and servers to a corresponding location according to the needs of the location to integrate various resources and improve computer usability, thereby saving 50%-70% of IT cost.
The typical realization of virtualization is to simulate, in a physical machine, at least one virtual computer, i.e. Virtual Machine, which is a completed computer system having entire functions of physical systems running in an isolated environment and simulated by software. Such virtual machines can host their own guest operating system and applications like physical computers and can have all components like physical computers, including simulations of a motherboard, hard disk, network card controller, etc. Although multiple virtual machines may share the physical resources of one computer, they are isolated from one another like different physical computers. For example, if there are four virtual machines in one physical server but one of them crashes, the other three can be still available. Because of such isolation, the usability and security of applications running in virtual environment is far better than that in traditional non-virtualized systems.
To keep isolated from one another, virtual machines retain independency of hardware resource distribution and share as few common physical resources as possible. Specifically, in memory management, a hypervisor between the physical platform and virtual machines assigns a separate segment of memory for each virtual machine, and each virtual machine only accesses its own memory.